High integration and miniaturization of semiconductor devices are accelerating every year.
For example, currently, patterns with a line width of approximately 45 nm are being formed by excimer exposure. However, in recent years, with the advance in the miniaturization of semiconductor devices, there is a demand to form patterns with a line width of 32 nm or less. Such fine processing is difficult to be handled by the conventional excimer exposure. Therefore, the use of extreme ultra violet (EUV) light having a shorter wavelength as the exposure light is being under consideration.
EUV light has a property of being easily absorbed by any substance.
Therefore, in photolithography (hereinafter also referred to as “EUV lithography”) which uses EUV light as exposure light, exposure is performed using a catoptric system. Specifically, EUV light is reflected from an original plate having an exposure pattern reflected thereon and a resist is exposed by the EUV light as reflection light. In this case, when foreign particles adhere to the original plate, since EUV light is absorbed or scattered by the foreign particles, a desired pattern may not be formed on the original plate.
Therefore, a method of protecting the EUV irradiation surface of the original plate with a pellicle has been taken into consideration.
The pellicle is configured to include a pellicle membrane for protecting a EUV irradiation surface of an original plate and a pellicle frame (frame body) that supports the pellicle film.
The pellicle membrane used in EUV lithography is required to have high transmittance with respect to EUV light, and resistance against decomposition and deformation in the event of irradiation of EUV light. As a pellicle membrane that satisfies such requirements, a crystalline silicon film such as a monocrystalline silicon film (for example, see Documents 1 and 2 below), an aluminum nitride film layered on a metal mesh (for example, see Document 3), a graphene film (for example, see Document 4), and the like are proposed.
Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2010-256434
Document 2: Japanese Patent Application Laid-Open (JP-A) No. 2009-116284
Document 3: Japanese Patent Application Laid-Open (JP-A) No. 2005-43895
Document 4: International Publication No. 2011/160861